First published in Notizbl. Bot. Gart. Berlin-Dahlem 14: 41 (1938)

Accepted by

Literature

Kew Bulletin

IUCN Standards and Petitions Subcommittee (2011). Guidelines for using the IUCN Red List Categories and Criteria. Version 9.0. Prepared by the Standards and Petitions Subcommittee [September 2011]. Downloadable from http://intranet.iucn.org/webfiles/doc/SSC/RedList/RedListGuidelines.pdf.